In an attempt to enhance the cleaning efficiency of carpets, various types of vacuum cleaners have heretofore been commercialized. Examples of such vacuum cleaners of the non-recirculating type include ones which utilize suctioned airflow to rotate a turbine to thereby drive a carpet cleaning brush means and ones which employ a small specialized motor rather than utilizing airflow to drive a carpet cleaning brush means or a carpet beating mechanism. The motor-driven brush means was disclosed in as old a patent as U.S. Pat. No. 2,592,710 in 1952, for example.
In the recirculating type of cleaner, the following approaches to enhancing the cleaning efficiency of carpets have been proposed as illustrated in FIGS. 1A-1E and 2A-2C: